#include <stdio.h>

int greatestCommonDivisor(int a,int b)
{
	if (a%b == 0)
		return b;
	else {
		int recurse = greatestCommonDivisor(b,a%b);
		return recurse;
	}
}


int main(void){
    int result = greatestCommonDivisor(6,7);
    printf("%d\n",result);
    return 0;
}